Recyclable dry-particle based adhesive electrode and methods of making same

ABSTRACT

A dry process based capacitor and method for using one or more recyclable electrode film structure is disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present invention is a divisional of U.S. application Ser. No.10/817,074, filed Apr. 2, 2004, entitled “Recyclable Dry-Particle BasedAdhesive Electrode and Methods of Making Same” which claims priorityfrom commonly assigned Provisional Application No. 60/486,002, filedJul. 9, 2003; commonly assigned Provisional Application No. 60/486,530,filed Jul. 10, 2003; commonly assigned Provisional Application No.60/498,346, filed Aug. 26, 2003; commonly assigned ProvisionalApplication No. 60/498,210, filed Aug. 26, 2003; commonly assignedProvisional Application No. 60/511,273, filed Oct. 14, 2003; andcommonly assigned Provisional Application No. 60/546,093, filed Feb. 19,2004. Each of these nonprovisional and provisional applications isincorporated herein by reference in their entirety.

FIELD OF THE INVENTION

The present invention relates generally to the field of energy storagedevices that are used to power modern technology. More particularly, thepresent invention relates to recyclable structures and methods formaking dry particle based adhesive electrode films for use in capacitorproducts.

BACKGROUND INFORMATION

Devices that are used to power modern technology are numerous. Inclusiveof such devices are capacitors, batteries, and fuel cells. With eachtype of device are associated positive and negative characteristics.Based on these characteristics decisions are made as to which device ismore suitable for use in a particular application. Overall cost of adevice is an important characteristic that can make or break a decisionas to whether a particular type of device is used. Double-layercapacitors, also referred to as ultracapacitors and super-capacitors,are energy storage devices that are able to store more energy per unitweight and unit volume than capacitors made with traditional technology.

Double-layer capacitors store electrostatic energy in a polarizedelectrode/electrolyte interface layer. Double-layer capacitors includetwo electrodes, which are separated from contact by a porous separator.The separator prevents an electronic (as opposed to an ionic) currentfrom shorting the two electrodes. Both the electrodes and the porousseparator are immersed in an electrolyte, which allows flow of the ioniccurrent between the electrodes and through the separator. At theelectrode/electrolyte interface, a first layer of solvent dipole and asecond layer of charged species is formed (hence, the name“double-layer” capacitor).

Although, double-layer capacitors can theoretically be operated atvoltages as high as 4.0 volts and possibly higher, current double-layercapacitor manufacturing technologies limit nominal operating voltages ofdouble-layer capacitors to about 2.5 to 2.7 volts. Higher operatingvoltages are possible, but at such voltages undesirable destructivebreakdown begins to occur, which in part may be due to interactions withimpurities and residues that can be introduced into, or attachthemselves to, electrodes during manufacture. For example, undesirabledestructive breakdown of double-layer capacitors is seen to appear atvoltages between about 2.7 to 3.0 volts.

Known capacitor electrode fabrication techniques utilize processingadditive based coating and/or extrusion processes. Both processesutilize binders, which typically comprise polymers or resins thatprovide cohesion between structures used to make the capacitor. Knowndouble-layer capacitors utilize electrode film and adhesive/binder layerformulations that have in common the use of one or more added processingadditive (also referred throughout as “additive”), variations of whichare known to those skilled in the arts as solvents, lubricants, liquids,plasticizers, and the like. When such additives are utilized in themanufacture of a capacitor product, the operating lifetime, as wellmaximum operating voltage, of a final capacitor product may becomereduced, typically because of undesirable chemical interactions that canoccur between residues of the additive(s) and a subsequently usedcapacitor electrolyte.

In a coating process, an additive (typically organic, aqueous, or blendsof aqueous and organic solvents) is used to dissolve binders within aresulting wet slurry. The wet slurry is coated onto a collector througha doctor blade or a slot die. The slurry is subsequently dried to removethe solvent. With prior art coating based processes, as layer thicknessdecreases, it becomes increasingly more difficult to achieve an evenhomogeneous layer, for example, wherein a uniform 5 micron thick coatingof an adhesive/binder layer is desired. The process of coating alsoentails high-cost and complicated processes. Furthermore, coatingprocesses require large capital investments, as well as high qualitycontrol to achieve a desired thickness, uniformity, top to bottomregistration, and the like.

In the prior art, a first wet slurry layer is coated onto a currentcollector to provide the current collector with adhesive/binder layerfunctionality. A second slurry layer, with properties that providefunctionality of a conductive electrode layer, may be coated onto thefirst coated layer. In another prior art example, an extruded layer canbe applied to the first coated layer to provide conductive electrodelayer functionality.

In the prior art process of forming an extruded conductive electrodelayer, binder and carbon particles are blended together with one or moreadditive. The resulting material has dough-like properties that allowthe material to be introduced into an extruder apparatus. The extruderapparatus fibrillates the binder and provides an extruded film, which issubsequently dried to remove most, but as discussed below, typically notall of the additive(s). When fibrillated, the binder acts as a matrix tosupport the carbon particles. The extruded film may be calendared manytimes to produce an electrode film of desired thickness and density.

Known methods for attaching additive/solvent based extruded electrodefilms and/or coated slurries to a current collector include theaforementioned precoating of a slurry of adhesive/binder. Pre-coatedslurry layers of adhesive/binder are used in the capacitor prior arts topromote electrical and physical contact with current collectors, and thecurrent collectors themselves provide a physical electrical contactpoint.

Impurities can be introduced or attach themselves during theaforementioned coating and/or extrusion processes, as well as duringprior and subsequent steps. Just as with additives, the residues ofimpurities can reduce a capacitor's operating lifetime and maximumoperating voltage. In order to reduce the amount of additive andimpurity in a final capacitor product, one or more of the various priorart capacitor structures described above are processed through a dryer.Drying processes introduce many manufacturing steps, as well asadditional processing apparatus. In the prior art, the need to provideadequate throughput requires that the drying time be limited to on theorder of hours, or less. However, with such short drying times,sufficient removal of additive and impurity is difficult to achieve.Even with a long drying time (on the order of days) the amounts ofremaining additive and impurity is still measurable, especially if theadditives or impurities have a high heat of absorption. Long dwell timeslimit production throughput and increase production and processequipment costs. Residues of the additives and impurities remain incommercially available capacitor products and can be measured to be onthe order of many parts-per-million.

Binder particles used in prior art additive based fibrillization stepsinclude polymers and polymer-like substances. Polymers and similarultra-high molecular weight substances capable of fibrillization arecommonly referred to as “fibrillizable binders” or “fibril-formingbinders.” Fibril-forming binders find use with powder like materials. Inone prior art process, fibrillizable binder and powder materials aremixed with solvent, lubricant, or the like, and the resulting wetmixture is subjected to high-shear forces to fibrillize the binderparticles. Fibrillization of the binder particles produces fibrils thateventually form a matrix or lattice for supporting a resultingcomposition of matter. In the prior art, the high shear forces can beprovided by subjecting the wet mixture comprising the binder to anextrusion process.

In the prior art, the resulting additive based extruded product can besubsequently processed in a high-pressure compactor, dried to remove theadditive, shaped into a needed form, and otherwise processed to obtainan end-product for a needed application. For purposes of handling,processing, and durability, desirable properties of the end producttypically depend on the consistency and homogeneity of the compositionof matter from which the product is made, with good consistency andhomogeneity being important requirements. Such desirable propertiesdepend on the degree of fibrillization of the polymer. Tensile strengthcommonly depends on both the degree of fibrillization of thefibrillizable binder, and the consistency of the fibril lattice formedby the binder within the material. When used as an electrode film,internal resistance of an end product is also important. Internalresistance may depend on bulk resistivity—volume resistivity on largescale—of the material from which the electrode film is fabricated. Bulkresistivity of the material is a function of the material's homogeneity;the better the dispersal of the conductive carbon particles or otherconductive filler within the material, the lower the resistivity of thematerial. When electrode films are used in capacitors, such as,electrochemical double-layer capacitors, capacitance per unit volume isyet another important characteristic for consideration. In double layercapacitors, capacitance increases with the specific surface area of theelectrode film used to make a capacitor electrode. Specific surface areais defined as the ratio of (1) the surface area of electrode filmexposed to an electrolytic solution when the electrode material isimmersed in the solution, and (2) the volume of the electrode film. Anelectrode film's specific surface area and capacitance per unit volumeare believed to improve with improvement in consistency and homogeneity.

In both the coating and extrusion processes, once an electrode film iscreated, if a problem arises or is found to have occurred during aprocess step, the film is typically discarded.

A need thus exists for new methods of producing inexpensive and reliablecapacitor electrode materials with one or more of the followingqualities: improved consistency and homogeneity of distribution ofbinder and active particles on microscopic and macroscopic scales;improved tensile strength of electrode film produced from the materials;decreased resistivity; and increased specific surface area. Yet anotherneed exists for capacitor electrodes fabricated from recycled materialswith these qualities. A further need is to provide capacitors andcapacitor electrodes without the use of processing additives.

SUMMARY

The present invention provides a high yield method for makinginexpensive, durable, and highly reliable dry electrode films andassociated structures for use in energy storage devices.

In one embodiment, an energy storage device product comprises a mix ofrecyclable carbon and binder particles. At least some of the mix may bedry fibrillized. The mix may comprise no processing additive.

In one embodiment, an energy storage device product, may comprise afilm, the film including a mix of particles, wherein at least some ofthe particles are recycled particles. The particles may be fibrillized.The recycled particles may be fibrillized. The film may be aself-supporting film. The film may comprise a thickness of less than 250microns. The film may comprise a length of at least 1 meter. The filmmay be coupled directly against a substrate. The film may comprisesubstantially no processing additive. The substrate may comprise acollector. The product may comprise a collector, and wherein the film iscoupled directly against a surface of the collector. The collector maycomprise two sides, wherein one film is calendered directly against oneside of the collector, wherein a second film is calendered directlyagainst a second side of the collector. The collector may be treated.The collector may be formed to comprise a roll. The roll may be disposedwithin a sealed aluminum housing. The product of claim 4, wherein atleast some of the particles comprise fibrillizable fluoropolymer andcarbon particles. The carbon particles comprise activated carbonparticles and conductive particles. At least some of the particles maycomprise thermoplastic particles.

In one embodiment, an energy storage product, may comprise a dry mix ofrecyclable dry binder and dry carbon particles, the particles formedinto a continuous self-supporting electrode film without the substantialuse of any processing additives. The processing additive not used mayinclude hydrocarbons, high boiling point solvents, antifoaming agents,surfactants, dispersion aids, water, pyrrolidone, mineral spirits,ketones, naphtha, acetates, alcohols, glycols, toluene, xylene, andIsopars™. At least some of the dry binder may comprise a fibrillized drybinder. The binder may be fibrillized by a high-pressure gas. Thehigh-pressure may comprise a pressure of more than 60 PSI. The gas maycomprise a water content of less than about 20 PPM.

In one embodiment, a method of making an energy storage device electrodecomprises the steps of forming an electrode film from a plurality ofparticles; and reusing one or more of the plurality of particles to formthe film. The plurality of particles may be dry fibrillized. The methodmay comprise a step of coupling a first side of the film to a collector.The step of reusing may comprise a step of fibrillizing the particlesafter the particles are used to make the electrode film. The binder maycomprise a fluoropolymer. The carbon particles may comprise conductivecarbon particles. The film may be self supporting. The particles maycomprise conductive carbon particles and activated carbon particles. Thefilm may be a heated dry film. The film may comprise a density of about0.50 to 0.70 gm/cm². The method may comprise between about 80% to 95%activated carbon, between about 0% to 15% conductive carbon, and betweenabout 3% to 15% fibrillizable fluoropolymer. The film may comprise athermoplastic.

In one embodiment, a capacitor comprises a plurality of dry processedparticles, the dry processed particles including recycled binder andconductive particles. At least some of the dry processed particles maybe formed as a self supporting dry electrode film. The capacitor maycomprise a current collector, wherein the dry processed particles arebonded to the current collector, wherein the current collector comprisesaluminum. The capacitor may comprise separator, wherein the dryprocessed particles are bonded to the separator. The separator maycomprise paper. The capacitor may be rated to operate at a maximumvoltage of 3.0 volts or less. The dry electrode film may comprise adensity of about 0.50 to 0.70 gm/cm². The dry processed particles may becompacted into a dry self-supporting electrode film by a single passcompaction device. The capacitor may comprise a sealed aluminum housing,wherein the dry processed particles are disposed within the housing. Thecapacitor may comprise a sealed aluminum housing, wherein the currentcollector is coupled to the housing by a laser weld. The capacitor maycomprise a jellyroll type electrode.

In one embodiment, a capacitor comprises a plurality of reusableparticles; a collector; the collector having two sides; and twoelectrode film layers, the two electrode film layers comprised of thereusable particles, wherein a first electrode film layer is bondeddirectly onto a first surface of the collector, and wherein a secondelectrode film layer is bonded directly onto a second surface of thecollector. The two electrode film layers may comprise substantially noprocessing additives. The two electrode layers may comprise dryfibrillized particles. The film layers may comprise substantially zeroresidues as determined by a chemical analysis of the layers beforeimpregnation by an electrolyte. The energy storage device may compriseone or more continuous self supporting intermixed film structurecomprised of reused carbon particles dry binder particles, the filmstructure consisting of about zero parts per million processingadditive. The additive may be selected from hydrocarbons, high boilingpoint solvents, antifoaming agents, surfactants, dispersion aids, water,pyrrolidone, mineral spirits, ketones, naphtha, acetates, alcohols,glycols, toluene, xylene, and Isopars™. The intermixed film structuremay be an electrode film. The electrode film may be an energy storagedevice electrode film. The electrode film may comprise a capacitorelectrode film.

In one embodiment, an energy storage device comprises a housing; acollector, the collector having an exposed surface; an electrolyte, theelectrolyte disposed within the housing; and an electrode film, theelectrode comprised of recycled particles, wherein the electrode film isimpregnated with the electrolyte, and wherein the electrode film iscoupled directly to the exposed surface. The electrode film may besubstantially insoluble in the electrolyte. The electrode may comprise adry binder, wherein the binder is substantially insoluble in theelectrolyte. The binder may comprise a thermoplastic, wherein thethermoplastic couples the electrode film to the collector. Theelectrolyte may be an acetonitrile type of electrolyte.

In one embodiment, an energy storage device structure comprises one ormore recyclable electrode film, wherein the one or more recyclableelectrode film is both conductive and adhesive, and wherein the one ormore recyclable electrode film is coupled directly to a currentcollector.

In one embodiment, an energy storage device structure comprises one ormore self-supporting recyclable dry process based electrode film. Thefilm may comprise conductive and adhesive particles. The adhesiveparticles may comprise a thermoplastic. The electrode may be a capacitorelectrode.

In one embodiment, an electrode comprises a collector; and a dry processbased electrode film, wherein the electrode film is coupled to thecollector, wherein the electrode film comprises conductive particles andbinder particles, and wherein between the collector and the electrodefilm there exists only one distinct interface. The binder particles maycomprise a thermoplastic. The conductive particles may compriseconductive carbon. The electrode film may comprise activated carbon. Theconductive particles may comprise a metal.

In one embodiment, an energy storage device structure comprises aplurality of intermixed recyclable dry processed carbon and binderparticles formed as an electrode, wherein as compared to an electrodeformed of a plurality of the same carbon and binder particles processedwith a processing additive, the intermixed dry processed carbon andbinder particles comprises less residue.

In one embodiment, a capacitor comprises a continuous compacted selfsupporting recyclable dry electrode film comprised of a dry mix of drybinder and dry carbon particles, the film coupled to a collector, thecollector shaped into a roll disposed within a sealed aluminum housing.The dry electrode film may comprise substantially no processingadditive.

In one embodiment, an energy storage device comprises dry processrecyclable electrode means for providing electrode functionality in anenergy storage device.

In one embodiment, a solventless method for manufacture of an energystorage device electrode comprises the steps of providing dry carbonparticles; providing dry binder particles; and forming the dry carbonand dry binder particles into an energy storage device electrode withoutthe substantial use of any hydrocarbons, high boiling point solvents,antifoaming agents, surfactants, dispersion aids, water, pyrrolidonemineral spirits, ketones, naphtha, acetates, alcohols, glycols, toluene,xylene, and/or Isopars™. In one embodiment, an energy storage deviceelectrode comprises substantial no hydrocarbons, high boiling pointsolvents, antifoaming agents, surfactants, dispersion aids, water,pyrrolidone mineral spirits, ketones, naphtha, acetates, alcohols,glycols, toluene, xylene, and/or Isopars™.

Other embodiments, benefits, and advantages will become apparent upon afurther reading of the following Figures, Description, and Claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a is a block diagram illustrating a method for making an energystorage device electrode film.

FIG. 1 b is a high-level front view of a jet-mill assembly used tofibrillize binder within a dry carbon particle mixture.

FIG. 1 c is a high-level side view of a jet-mill assembly shown in FIG.1 b;

FIG. 1 d is a high-level top view of the jet-mill assembly shown inFIGS. 1 b and 1 c.

FIG. 1 e is a high-level front view of a compressor and a compressed airstorage tank used to supply compressed air to a jet-mill assembly.

FIG. 1 f is a high-level top view of the compressor and the compressedair storage tank shown in FIG. 1 e, in accordance with the presentinvention.

FIG. 1 g is a high-level front view of the jet-mill assembly of FIGS. 1b-d in combination with a dust collector and a collection container.

FIG. 1 h is a high-level top view of the combination of FIGS. 1 f and 1g.

FIGS. 1 i, 1 j, and 1 k illustrate effects of variations in feed rate,grind pressure, and feed pressure on tensile strength in length, tensilestrength in width, and dry resistivity of electrode materials.

FIG. 1 m illustrates effects of variations in feed rate, grind pressure,and feed pressure on internal resistance.

FIG. 1 n illustrates effects of variations in feed rate, grind pressure,and feed pressure on capacitance.

FIG. 1 p illustrates effect of variation in feed pressure on internalresistance of electrodes, and on the capacitance of double layercapacitors using such electrodes.

FIG. 2 a shows an apparatus for forming a structure of an electrode.

FIG. 2 b shows a degree of intermixing of dry particles.

FIG. 2 c shows a gradient of particles within a dry film.

FIG. 2 d shows a distribution of the sizes of dry binder and conductivecarbon particles.

FIGS. 2 e-f, show carbon particles as encapsulated by dissolved binderof the prior art and dry carbon particles as attached to dry binder ofthe present invention.

FIG. 2 g shows a system for forming a structure for use in an energystorage device.

FIG. 3 is a side representation of one embodiment of a system forbonding electrode films to a current collector for use in an energystorage device.

FIG. 4 illustrates a method for recycling/reusing dry particles andstructures made therefrom.

FIG. 5 a is a side representation of one embodiment of a structure of anenergy storage device electrode.

FIG. 5 b is a top representation of one embodiment of an electrode.

FIG. 6 is a side representation of a rolled electrode coupled internallyto a housing.

FIG. 7 a illustrates capacitance vs. number of full charge/dischargecharge cycles.

FIG. 7 b illustrates resistance vs. number of full charge/dischargecharge cycles.

FIG. 7 c illustrates effects of electrolyte on specimens of electrodes.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to several embodiments of theinvention that are illustrated in the accompanying drawings. Whereverpossible, same or similar reference numerals are used to refer to thesame or similar elements, or steps and/or elements used therein.

In accordance with embodiments of the present invention, an inexpensive,long lasting, reliable dry particle capacitor, capacitor electrode, andone or more recycled/recyclable structures thereof, as well as methodsfor making the same are described. The present invention providesdistinct advantages when compared to those of the additive-basedcoating/extruder devices of the prior art, which include the ability toutilize structures that, if needed, can be reused.

The energy storage devices and methods associated with the presentinvention do not use the one or more prior art processing aides oradditives associated with coating and extrusion based processes(hereafter referred throughout as “processing additive” or “additive”),including: added solvents, liquids, lubricants, plasticizers, and thelike. As well, one or more associated additive removal steps, postcoating treatments such as curing or cross-linking, drying step(s) andapparatus associated therewith, and the like, are eliminated. Becauseadditives are not used during manufacture, a final electrode product isnot subject to chemical interactions that may occur between theaforementioned prior art residues of such additives and a subsequentlyused electrolyte. Because binders that are dissolvable by additives donot need to be used with present invention, a wider class of orselection of binders may be used than in the prior art. Such binders canbe selected to be completely or substantially insoluble and nonswellablein typically used electrolytes, an advantage, which when combined with alack of additive based impurities or residues such electrolytes canreact to, allows that a much more reliable and durable energy storagedevice may be provided. A high throughput method for making more durableand more reliable energy storage devices is thus provided.

Referring now to FIG. 7 a, there are seen capacitance vs. number of fullcharge/discharge charge cycles tests for both a prior art energy storagedevice 5 manufactured using processing additives and an embodiment of anenergy storage device 6 comprising structures manufactured using noprocessing additives according to one or more of the principlesdescribed further herein.

Device 5 incorporates in its design a prior art processingadditive-based electrode available from W.L Gore & Associates, Inc. 401Airport Rd., Elkton, Md. 21922, 410-392-444, under the EXCELLERATOR™brand of electrode. The EXCELLERATOR™ brand of electrode was configuredin a jellyroll configuration within an aluminum housing to comprise adouble-layer capacitor. Device 6 was also configured as a similar Faraddouble-layer capacitor in a similar form factor housing, but usinginstead a dry electrode film 33 (as referenced in FIG. 2 g describedbelow).

The dry electrode film 33 was adhered to a collector by an adhesivecoating sold under the trade name Electrodag® EB-012 by Acheson ColloidsCompany, 1600 Washington Ave., Port Huron, Mich. 48060, Telephone1-800-984-5581. Dry film 33 was manufactured utilizing no processingadditives in a manner described further herein.

Those skilled in the art will identify that high capacitance (forexample, 1000 Farads and above) capacitor products that are soldcommercially are derated to reflect an initial drop (on the order of 10%or so) in capacitance that may occur during the first 5000 or socapacitor charge discharge cycles, in other words, a rated 2600 Faradcapacitor sold commercially may initially be a 2900 Farad or higherrated capacitor. After the first 5000 cycles or so, those skilled in theart will identify that under normal expected use, (normal temperature,average cycle discharge duty cycle, etc), a capacitors rated capacitancemay decrease at a predictable reduced rate, which may be used to predicta capacitors useful life. The higher the initial capacitor value neededto achieve a rated capacitor value, the more capacitor material isneeded, and thus, the higher the cost of the capacitor.

In the FIGS. 7 a and 7 b embodiments, both devices 5 and 6 were testedwithout any preconditioning. The initial starting capacitance of devices5 and 6 was about 2800 Farad. The test conditions were such that at roomtemperature, both devices 5 and 6 were full cycle charged at 100 amps to2.5 volts and then discharged to 1.25 volts. Both devices were chargedand discharged in this manner continuously. The test was performed forapproximately 70,000 cycles for the prior art device 5, and forapproximately 120,000 cycles for the device 6. Those skilled in the artwill identify that such test conditions are considered to be high stressconditions that capacitor products are not typically expected to besubject to, but were nevertheless conducted to demonstrate thedurability of device 6. As indicated by the results, the prior artdevice 5 experienced a drop of about 30% in capacitance by the time70,000 full charge cycles occurred, whereas at 70,000 and 120,000 cyclesdevice 6 experienced only a drop of about 15% and 16%, respectively.Device 6 is shown to experience a predictable decrease in capacitancethat can be modeled to indicate that cycling of the capacitor up toabout 0.5 million, 1 million, and 1.5 million cycles can be achievedunder the specific conditions with respective drops of 21%, 23%, and 24%in capacitance. At 70,000 cycles it is shown that device 6 madeaccording to one or more of the embodiments disclosed herein experiencedabout 50% less in capacitance drop than a processing additive basedprior art device 5 (about 15% vs. 30%, respectively). At about 120,000cycles it is shown that device 6 made according to one or moreembodiments disclosed herein experienced only about 17% capacitancedrop. At 1 million cycles it is envisioned that device 6 will experienceless than 25% drop from its initial capacitance.

Referring now to FIG. 7 b, there are seen resistance vs. number of fullcharge/discharge charge cycles tests for both a prior art energy storagedevice 5 manufactured using processing additives and an embodiment of anenergy storage device 6. As indicated by the results, the prior artdevice 5 experienced an increase in resistance over that of device 6. Asseen, device 6 experiences a minimal increase in resistance (less than10% over 100,000 cycles) as compared to device 5 (100% increase over75,000 cycles).

Referring now to FIG. 7 c, there are seen physical specimens ofelectrode obtained from devices 5, 6, and 7 shown after one week and 1month of immersion in 1.5 M tetramethylammonium or tetrafluoroborate inacetonitrile electrolyte at a temperature of 85 degrees centigrade. Theelectrode sample from device 5 comprises the processing additive basedEXCELLERATOR™ brand of electrode film discussed above, and the electrodesample of device 7 comprises a processing additive based electrode filmobtained from a 5 Farad NESCAP double-layer capacitor product,Wonchun-Dong 29-9, Paldal-Ku, Suwon, Kyonggi, 442-380, Korea, Telephone:+82 31 219 0682. As seen, electrodes from devices 5 and 7 show damageafter 1 week and substantial damage after 1 month immersion inacetonitrile electrolyte. In contrast, an electrode from a device 6 madeof one or more of the embodiments described further herein shows novisual damage, even after one year (physical specimen not shown) ofimmersion in acetonitrile electrolyte.

Accordingly, in one embodiment, when charged at 100 amps to 2.5 voltsand then discharged to 1.25 volts over 120,000 cycles a device 6experiences less than a 30 percent drop in capacitance. In oneembodiment, when charged at 100 amps to 2.5 volts and then discharged to1.25 volts over 70,000 cycles a device 6 experiences less than a 30percent drop in capacitance. In one embodiment, when charged at 100 ampsto 2.5 volts and then discharged to 1.25 volts over 70,000 cycles adevice 6 experiences less than a 5 percent drop in capacitance. In oneembodiment, a device 6 is capable of being charged at 100 amps to 2.5volts and then discharged to 1.25 volts over 1,000,000 cycles with lessthan a 30% drop in capacitance. In one embodiment, a device 6 is capableof being charged at 100 amps to 2.5 volts and then discharged to 1.25volts over 1,500,000 cycles with less than a 30% drop in capacitance. Inone embodiment, when charged at 100 amps to 2.5 volts and thendischarged to 1.25 volts over 70,000 cycles a device 6 experiences anincrease in resistance of less than 100 percent. In one embodiment, amethod of using a device 6 comprises the steps of: (a) charging thedevice from 1.25 volts to 2.5 volts at 100 amps; (b) discharging thedevice to 1.25 volts; and (c) measuring less than a 30% drop in aninitial capacitance of the device after repeating step (a) and step (b)70,000 times. In one embodiment, a method of using a device 6 comprisesthe steps of: (a) charging the device from 1.25 volts to 2.5 volts at100 amps; (b) discharging the device to 1.25 volts; and (c) measuringless than a 5% drop in an initial capacitance of the device afterrepeating step (a) and step (b) 70,000 times.

In the embodiments that follow, it will be understood that reference tono-use and non-use of additive(s) in the manufacture of an energystorage device according to the present invention takes into accountthat electrolyte may be used during a final electrode electrolyteimmersion/impregnation step. An electrode electrolyteimmersion/impregnation step is typically utilized prior to providing afinal finished capacitor electrode in a sealed housing. Furthermore,even though additives, such as solvents, liquids, and the like, are notused in the manufacture of embodiments disclosed herein, duringmanufacture, a certain amount of impurity, for example, moisture, may beabsorbed or attach itself from a surrounding environment. Those skilledin the art will understand that the dry particles used with embodimentsand processes disclosed herein may also, prior to their being providedby particle manufacturers as dry particles, have themselves beenpre-processed with additives and, thus, comprise one or more pre-processresidue. For these reasons, despite the non-use of additives, one ormore of the embodiments and processes disclosed herein may require adrying step (which, however, if performed with embodiments of thepresent invention, can be much shorter than the drying steps of theprior art) prior to a final electrolyte impregnation step so as toremove/reduce such aforementioned pre-process residues and impurities.It is identified that even after one or more drying step, trace amountsof the aforementioned pre-process residues and impurities may be presentin the prior art, as well as embodiments described herein.

In general, because both the prior art and embodiments of the presentinvention obtain base particles and materials from similarmanufacturers, and because they may be exposed to similar pre-processenvironments, measurable amounts of prior art pre-process residues andimpurities may be similar in magnitude to those of embodiments of thepresent invention, although variations may occur due to differences inpre-processes, environmental effects, etc. In the prior art, themagnitude of such pre-process residues and impurities is smaller thanthat of the residues and impurities that remain and that can be measuredafter processing additives are used. This measurable amount ofprocessing additive based residues and impurities can be used as anindicator that processing additives have been used in a prior art energystorage device product. The lack of such measurable amounts ofprocessing additive can as well be used to distinguish the non-use ofprocessing additives in embodiments of the present invention.

Table 1 indicates the results of a chemical analysis of a prior artelectrode film and an embodiment of a dry electrode film made inaccordance with principles disclosed further herein. The chemicalanalysis was conducted by Chemir Analytical Services, 2672 Metro Blvd.,Maryland Heights, Mo. 63043, Phone 314-291-6620. Two samples wereanalyzed with a first sample (Chemir 533572) comprised of finely groundpowder obtained from a prior art additive based electrode film soldunder the EXCELLERATOR™ brand of electrode film by W.L Gore &Associates, Inc. 401 Airport Rd., Elkton, Md. 21922, 410-392-444. Asecond sample (Chemir 533571) comprised a thin black sheet of materialcut into ⅛ to 1 inch sided irregularly shaped pieces obtained from a dryfilm 33 (as discussed in FIG. 2 g below). The second sample (Chemir533571) comprised a particle mixture of about 80% to 90% activatedcarbon, about 0% to 15% conductive carbon, and about 3% to 15% PTFEbinder by weight. Suitable carbon powders are available from a varietyof sources, including YP-17 activated carbon particles sold by KurarayChemical Co., LTD, Shin-hankyu Bldg. 9F Blvd. C-237, 1-12-39 Umeda,Kiata-ku, Osaka 530-8611, Japan; and BP 2000 conductive particles soldby Cabot Corp. 157 Concord Road, P.O. Box 7001, Billerica, Mass.01821-7001, Phone: 978 663-3455. A tared portion of prior art sampleChemir 53372 was transferred to a quartz pyrolysis tube. The tube withits contents was placed inside of a pyrolysis probe. The probe was theninserted into a valved inlet of a gas chromatograph. The effluent of thecolumn was plumbed directly into a mass spectrometer that served as adetector. This configuration allowed the sample in the probe to beheated to a predetermined temperature causing volatile analytes to beswept by a stream of helium gas into the gas into the gas chromatographand through the analytical column, and to be detected by the massspectrometer. The pyrolysis probe was flash heated from ambienttemperature at a rate of 5 degrees C./millisecond to 250 degrees C. andheld constant for 30 seconds. The gas chromatograph was equipped with a30 meter Agilent. DB-5 analytical column. The gas chromatograph oventemperature was as follows: the initial temperature was held at 45degrees C. for 5 minutes and then was ramped at 20 degrees C. to 300degrees C. and held constant for 12.5 minutes. A similar procedure wasconducted for sample 53371 of a dry film 33. Long chain branchedhydrocarbon olefins were detected in both samples, with 2086 parts permillion (PPM) detected in the prior art sample, and with 493 PPMdetected in dry film 33. Analytes dimethylamine and a substituted alkylpropanoate were detected in sample Chemir 53372 with 337 PPM and werenot detected in sample Chemir 53371. It is envisioned that futureanalysis of other prior art additive based electrode films will providesimilar results with which prior art use of processing additives, orequivalently, the non-use of additives of embodiments described herein,can be identified and distinguished.

One or more prior art additives, impurities, and residues that exist in,or are utilized by, and that may be present in lower quantities inembodiments of the present invention than the prior art, include:hydrocarbons, high boiling point solvents, antifoaming agents,surfactants, dispersion aids, water, pyrrolidone mineral spirits,ketones, naphtha, acetates, alcohols, glycols, toluene, xylene,Isopars™, plasticizers, and the like.

TABLE 1 Pyrolysis GC/MS Analysis Retention Chemir 53372 Time in MinutesChemir 53371 (Prior Art) 1.65 0 PPM 0 PPM 12.3 0 PPM 0 PPM 13.6 0 PPMButylated hydroxyl toluene 337 PPM 20.3 0 PPM 0 PPM 20.6 A long chain Along chain branched branched hydrocarbon hydrocarbon olefin 493 PPM 2086PPM

Referring now to FIG. 1 a, a block diagram illustrating a process formaking a dry particle based energy storage device is shown. As usedherein, the term “dry” implies non-use of additives during process stepsdescribed herein, other than during a final impregnating electrolytestep. The process shown in FIG. 1 a begins by blending dry carbonparticles and dry binder together. As previously discussed, one or moreof such dry carbon particles, as supplied by carbon particlemanufacturers for use herein, may have been pre-processed. Those skilledin the art will understand that depending on particle size, particlescan be described as powders and the like, and that reference toparticles is not meant to be limiting to the embodiments describedherein, which should be limited only by the appended claims and theirequivalents. For example, within the scope of the term “particles,” thepresent invention contemplates powders, spheres, platelets, flakes,fibers, nano-tubes, and other particles with other dimensions and otheraspect ratios. In one embodiment, dry carbon particles as referencedherein refers to activated carbon particles 12 and/or conductiveparticles 14, and binder particles 16 as referenced herein refers to aninert dry binder. In one embodiment, conductive particles 14 compriseconductive carbon particles. In one embodiment, conductive particles 14comprise conductive graphite particles. In one embodiment, it isenvisioned that conductive particles 14 comprise a metal powder or thelike. In one embodiment, dry binder 16 comprises a fibrillizablefluoropolymer, for example, polytetrafluoroethylene (PTFE) particles.Other possible fibrillizable binders include ultra-high molecular weightpolypropylene, polyethylene, co-polymers, polymer blends and the like.It is understood that the present invention should not be limited by thedisclosed or suggested particles and binder, but rather, by the claimsthat follow. In one embodiment, particular mixtures of particles 12, 14,and binder 16 comprise about 50% to 99% activated carbon, about 0% to25% conductive carbon, and/or about 0.5% to 50% binder by weight. In amore particular embodiment, particle mixtures include about 80% to 90%activated carbon, about 0% to 15% conductive carbon, and about 3% to 15%binder by weight. In one embodiment, the activated carbon particles 12comprise a mean diameter of about 10 microns. In one embodiment, theconductive carbon particles 14 comprise diameters less than 20 microns.In one embodiment, the binder particles 16 comprise a mean diameter ofabout 450 microns. Suitable carbon powders are available from a varietyof sources, including YP-17 activated carbon particles sold by KurarayChemical Co., LTD, Shin-hankyu Bldg. 9F Blvd. C-237, 1-12-39 Umeda,Kiata-ku, Osaka 530-8611, Japan; and BP 2000 conductive particles soldby Cabot Corp. 157 Concord Road, P.O. Box 7001, Billerica, Mass.01821-7001, Phone: 978 663-3455.

In step 18, particles of activated carbon, conductive carbon, and binderprovided during respective steps 12, 14, and 16 are dry blended togetherto form a dry mixture. In one embodiment, dry particles 12, 14, and 16are blended for 1 to 10 minutes in a V-blender equipped with a highintensity mixing bar until a uniform dry mixture is formed. Thoseskilled in the art will identify that blending time can vary based onbatch size, materials, particle size, densities, as well as otherproperties, and yet remain within the scope of the present invention.With reference to blending step 18, in one embodiment, particle sizereduction and classification can be carried out as part of the blendingstep 18, or prior to the blending step 18. Size reduction andclassification may improve consistency and repeatability of theresulting blended mixture and, consequently, of the quality of theelectrode films and electrodes fabricated from the dry blended mixture.

After dry blending step 18, dry binder 16 within the dry particles isfibrillized in a dry fibrillizing step 20. The dry fibrillizing step 20is effectuated using a dry solventless and liquidless high sheartechnique. During dry fibrillizing step 20, high shear forces areapplied to dry binder 16 in order to physically stretch it. Thestretched binder forms a network of thin web-like fibers that act toenmesh, entrap, bind, and/or support the dry particles 12 and 14. In oneembodiment, fibrillizing step 20 may be effectuated using a jet-mill.

Referring to now to FIGS. 1 b, 1 c, and 1 d, there is seen,respectively, front, side, and top views of a jet-mill assembly 100 usedto perform a dry fibrillization step 20. For convenience, the jet-millassembly 100 is installed on a movable auxiliary equipment table 105,and includes indicators 110 for displaying various temperatures and gaspressures that arise during operation. A gas input connector 115receives compressed air from an external supply and routes thecompressed air through internal tubing (not shown) to a feed air hose120 and a grind air hose 125, which both lead and are connected to ajet-mill 130. The jet-mill 130 includes: (1) a funnel-like materialreceptacle device 135 that receives compressed feed air from the feedair hose 120, and the blended carbon-binder mixture of step 18 from afeeder 140; (2) an internal grinding chamber where the carbon-bindermixture material is processed; and (3) an output connection 145 forremoving the processed material. In the illustrated embodiment, thejet-mill 130 is a 4-inch Micronizer® model available from Sturtevant,Inc., 348 Circuit Street, Hanover, Mass. 02339; telephone number (781)829-6501. The feeder 140 is an AccuRate® feeder with a digital dialindicator model 302M, available from Schenck AccuRate®, 746 E. MilwaukeeStreet, P.O. Box 208, Whitewater, Wis. 53190; telephone number (888)742-1249. The feeder includes the following components: a 0.33 cubic ft.internal hopper; an external paddle agitation flow aid; a 1.0-inch, fullpitch, open flight feed screw; a % hp, 90VDC, 1,800 rpm, TENV electricmotor drive; an internal mount controller with a variable speed, 50:1turndown ratio; and a 110 Volt, single-phase, 60 Hz power supply with apower cord. The feeder 140 dispenses the carbon-binder mixture providedby step 18 at a preset rate. The rate is set using the digital dial,which is capable of settings between 0 and 999, linearly controlling thefeeder operation. The highest setting of the feeder dial corresponds toa feeder output of about 12 kg per hour.

The feeder 140 appears in FIGS. 1 b and 1 d, but has been omitted fromFIG. 1 c, to prevent obstruction of view of other components of thejet-mill 130. The compressed air used in the jet-mill assembly 100 isprovided by a combination 200 of a compressor 205 and a compressed airstorage tank 210, illustrated in FIGS. 1 e and 1 f; FIG. 1 e is a frontview and FIG. 1 f is a top view of the combination 200. The compressor205 used in this embodiment is a GA 30-55C model available from AtlasCopco Compressors, Inc., 161 Lower Wesffield Road, Holyoke, Mass. 01040;telephone number (413) 536-0600. The compressor 205 includes thefollowing features and components: air supply capacity of 180 standardcubic feet per minute (“SCFM”) at 125 PSIG; a 40-hp, 3-phase, 60 HZ, 460VAC premium efficiency motor; a WYE-delta reduced voltage starter;rubber isolation pads; a refrigerated air dryer; air filters and acondensate separator; an air cooler with an outlet 206; and an aircontrol and monitoring panel 207. The 180-SCFM capacity of thecompressor 205 is more than sufficient to supply the 4-inch Micronizer®jet-mill 130, which is rated at 55 SCFM. The compressed air storage tank210 is a 400-gallon receiver tank with a safety valve, an automaticdrain valve, and a pressure gauge. The compressor 205 providescompressed air to the tank 205 through a compressed air outlet valve206, a hose 215, and a tank inlet valve 211.

It is identified that the compressed air provided under high-pressure bycompressor 205 is preferably as dry as possible. Thus, in oneembodiment, an appropriately placed in-line filter and/or dryer may beadded. In one embodiment, a range of acceptable dew point for the air isabout −20 to −40 degrees F., and a water content of less than 20 ppm.Although discussed as being effectuated by high-pressure air, it isunderstood that other sufficiently dry gases are envisioned as beingused to fibrillize binder particles utilized in embodiments of thepresent invention, for example, oxygen, nitrogen, helium, and the like.

In the jet-mill 130, the carbon-binder mixture is inspired by venturiand transferred by the compressed feed air into a grinding chamber,where the fibrillization of the mixture takes place. In one embodiment,the grinding chamber is lined with a ceramic such that abrasion of theinternal walls of the jet-mill is minimized and so as to maintain purityof the resulting jet-milled carbon-binder mixture. The grinding chamber,which has a generally cylindrical shape, includes one or more nozzlesplaced circumferentially. The nozzles discharge the compressed grind airthat is supplied by the grind air hose 125. The compressed air jetsinjected by the nozzles accelerate the carbon-binder particles and causepredominantly particle-to-particle collisions, although someparticle-wall collisions also take place. The collisions dissipate theenergy of the compressed air relatively quickly, fibrillizing the drybinder 16 within the mixture and embedding carbon particle 12 and 14aggregates and agglomerates into the lattice formed by the fibrillizedbinder. The collisions may also cause size reduction of the carbonaggregates and agglomerates. The colliding particles 12, 14, and 16spiral towards the center of the grinding chamber and exit the chamberthrough the output connection 145.

Referring now to FIGS. 1 g and 1 h, there are seen front and top views,respectively, of the jet-mill assembly 100, a dust collector 160, and acollection container 170 (further referenced in FIG. 2 a as container20). In one embodiment, the fibrillized carbon-binder particles thatexit through the output connection 145 are guided by a discharge hose175 from the jet-mill 130 into a dust collector 160. In the illustratedembodiment, the dust collector 160 is model CL-7-36-11 available fromUltra Industries, Inc., 1908 DeKoven Avenue, Racine, Wis. 53403;telephone number (262) 633-5070. Within the dust collector 160 theoutput of the jet-mill 130 is separated into (1) air, and (2) a dryfibrillized carbon-binder particle mixture 20. The carbon-binder mixtureis collected in the container 170, while the air is filtered by one ormore filters and then discharged. The filters, which may be internal orexternal to the dust collector 160, are periodically cleaned, and thedust is discarded. Operation of the dust collector is directed from acontrol panel 180.

It has been identified that a dry compounded material, which is providedby dry fibrillization step 20, retains its homogeneous particle likeproperties for a limited period of time. In one embodiment, because offorces, for example, gravitational forces exerted on the dry particles12, 14, and 16, the compounded material begins to settle such thatspaces and voids that exist between the dry particles 12, 14, 16 afterstep 20 gradually become reduced in volume. In one embodiment, after arelatively short period of time, for example 10 minutes or so, the dryparticles 12, 14, 16 compact together and begin to form clumps or chunkssuch that the homogeneous properties of the compounded material may bediminished and/or such that downstream processes that require freeflowing compounded materials are made more difficult or impossible toachieve. Accordingly, in one embodiment, it is identified that a drycompounded material as provided by step 20 should be utilized before itshomogeneous properties are no longer sufficiently present and/or thatsteps are taken to keep the compounded material sufficiently aerated toavoid clumping.

It should be noted that the specific processing components described sofar may vary as long as the intent of the embodiments described hereinis achieved. For example, techniques and machinery that are envisionedfor potential use to provide high shear forces to effectuate a dryfibrillization step 20 include jet-milling, pin milling, impactpulverization, and hammer milling, and other techniques and apparatus.Further in example, a wide selection of dust collectors can be used inalternative embodiments, ranging from simple free-hanging socks tocomplicated housing designs with cartridge filters or pulse-cleanedbags. Similarly, other feeders can be easily substituted in the assembly100, including conventional volumetric feeders, loss-weight volumetricfeeders, and vibratory feeders. The size, make, and other parameters ofthe jet-mill 130 and the compressed air supply apparatus (the compressor205 and the compressed air storage tank 210) may also vary and yet bewithin the scope of the present invention.

The present inventors have performed a number of experiments toinvestigate the effects of three factors in the operation of jet-millassembly 100 on qualities of the dry compounded material provided by dryfibrillization step 20, and on compacted/calendered electrode filmsfabricated therefrom. The three factors are these: (1) feed airpressure, (2) grind air pressure, and (3) feed rate. The observedqualities included tensile strength in width (i.e., in the directiontransverse to the direction of movement of a dry electrode film in ahigh-pressure calender during a compacting process); tensile strength inlength (i.e., in the direction of the dry film movement); resistivity ofthe jet-mill processed mixture provided by dry fibrillization step 20;internal resistance of electrodes made from the dry electrode film in adouble layer capacitor application; and specific capacitance achieved ina double layer capacitor application. Resistance and specificcapacitance values were obtained for both charge (up) and discharge(down) capacitor cycles.

The design of experiments (“DOE”) included a three-factorial, eightexperiment investigation performed with dry electrode films dried for 3hours under vacuum conditions at 160 degrees Celsius. Five or sixsamples were produced in each of the experiments, and values measured onthe samples of each experiment were averaged to obtain a more reliableresult. The three-factorial experiments included the following pointsfor the three factors:

1. Feed rate was set to indications of 250 and 800 units on the feederdial used. Recall that the feeder rate has a linear dependence on thedial settings, and that a full-scale setting of 999 corresponds to arate of production of about 12 kg per hour (and therefore asubstantially similar material consumption rate). Thus, settings of 250units corresponded to a feed rate of about 3 kg per hour, while settingsof 800 units corresponded to a feed rate of about 9.6 kg per hour. Inaccordance with the standard vernacular used in the theory of design ofexperiments, in the accompanying tables and graphs the former setting isdesignated as a “0” point, and the latter setting is designated as a “1”point.2. The grind air pressure was set alternatively to 85 psi and 110 psi,corresponding, respectively, to “0” and “1” points in the accompanyingtables and graphs.3. The feed air pressure (also known as inject air pressure) was set to60 and 70 psi, corresponding, respectively, to “0” and “1” points.

Turning first to tensile strength measurements, strips of standard widthwere prepared from each sample, and the tensile strength measurement ofeach sample was normalized to a one-mil thickness. The results fortensile strength measurements in length and in width appear in Tables 2and 3 below.

TABLE 2 Tensile Strength in Length FACTORS (Feed Rate, SAMPLE TENSILENORMALIZED Exp. Grind psi, Feed DOE THICKNESS STRENGTH IN TENSILESTRENGTH No. psi) POINTS (mil) LENGTH (grams) IN LENGTH (g/mil) 1250/85/60 0/0/0 6.1 123.00 20.164 2 250/85/70 0/0/1 5.5 146.00 26.545 3250/110/60 0/1/0 6.2 166.00 26.774 4 250/110/70 0/1/1 6.1 108.00 17.7055 800/85/60 1/0/0 6.0 132.00 22.000 6 800/85/70 1/0/1 5.8 145.00 25.0007 800/110/60 1/1/0 6.0 135.00 22.500 8 800/110/70 1/1/1 6.2 141.0022.742

TABLE 3 Tensile Strength in Width Factors Sample Normalized Tensile(Feed Rate, DOE Thickness Tensile Strength Strength Exp. No Grind psi,Feed psi) Points (mil) in Length (grams) in Length (g/mil) 1 250/85/600/0/0 6.1 63.00 10.328 2 250/85/70 0/0/1 5.5 66.00 12.000 3 250/110/600/1/0 6.2 77.00 12.419 4 250/110/70 0/1/1 6.1 59.00 9.672 5 800/85/601/0/0 6.0 58.00 9.667 6 800/85/70 1/0/1 5.8 70.00 12.069 7 800/110/601/1/0 6.0 61.00 10.167 8 800/110/70 1/1/1 6.2 63.00 10.161

Table 4 below presents resistivity measurements of a jet-mill-dry blendof particles provided by dry fibrillization step 20. Note that theresistivity measurements were taken before the mixture was processedinto a dry electrode film.

TABLE 4 Dry Resistance Factors (Feed Rate, Grind psi, DRY RESISTANCEExp. No. Feed psi) DOE Points (Ohms) 1 250/85/60 0/0/0 0.267 2 250/85/700/0/1 0.229 3 250/110/60 0/1/0 0.221 4 250/110/70 0/1/1 0.212 5800/85/60 1/0/0 0.233 6 800/85/70 1/0/1 0.208 7 800/110/60 1/1/0 0.241 8800/110/70 1/1/1 0.256

Referring now to FIGS. 1 i, 1 j, and 1 k, there are illustrated theeffects of the three factors on the tensile strength in length, tensilestrength in width, and dry resistivity. Note that each end-point for aparticular factor line (i.e., the feed rate line, grind pressure line,or inject pressure line) on a graph corresponds to a measured value ofthe quality parameter (i.e., tensile strength or resistivity) averagedover all experiments with the particular key factor held at either “0”or “1,” as the case may be. Thus, the “0” end-point of the feed rateline (the left most point) represents the tensile strength averaged overexperiments numbered 1-4, while the “1” end-point on the same linerepresents the tensile strength averaged over experiments numbered 4-8.As can be seen from FIGS. 1 i and 1 j, increasing the inject pressurehas a moderate to large positive effect on the tensile strength of anelectrode film. At the same time, increasing the inject pressure has thelargest effect on the dry resistance of the powder mixture, swamping theeffects of the feed rate and grind pressure. The dry resistancedecreases with increasing the inject pressure. Thus, all three qualitiesbenefit from increasing the inject pressure.

In Table 5 below we present data for final capacitances measured indouble-layer capacitors utilizing dry electrode films made from dryfibrillized particles as described herein by each of the 8 experiments,averaged over the sample size of each experiment. Note that C_(up)refers to the capacitances measured when charging double-layercapacitors, while C_(up) values were measured when discharging thecapacitors. As in the case of tensile strength data, the capacitanceswere normalized to the thickness of the electrode film. In this case,however, the thicknesses have changed, because the dry film hasundergone compression in a high-pressure nip during the process ofbonding the film to a current collector. It is noted in obtaining theparticular results of Table 5, the dry electrode film was bonded to acurrent collector by an intermediate layer of adhesive. Normalizationwas carried out to the standard thickness of 0.150 millimeters.

TABLE 5 C_(up) and C_(down) Factors (Feed Rate, Sample Exp. Grind psi,DOE Thickness C_(up) Normalized C_(down) NORMALIZED No. Feed psi) Points(mm) (Farads) C_(up) (Farads) (Farads) C_(down) (Farads) 1 250/85/600/0/0 0.149 1.09 1.097 1.08 1.087 2 250/85/70 0/0/1 0.133 0.98 1.1050.97 1.094 3 250/110/60 0/1/0 0.153 1.12 1.098 1.11 1.088 4 250/110/700/1/1 0.147 1.08 1.102 1.07 1.092 5 800/85/60 1/0/0 0.148 1.07 1.0841.06 1.074 6 800/85/70 1/0/1 0.135 1.00 1.111 0.99 1.100 7 800/110/601/1/0 0.150 1.08 1.080 1.07 1.070 8 800/110/70 1/1/1 0.153 1.14 1.1181.14 1.118

In Table 6 we present data for resistances measured in each of the 8experiments, averaged over the sample size of each experiment. Similarlyto the previous table, R_(up) designates resistance values measured whencharging double-layer capacitors, while R_(down) refers to resistancevalues measured when discharging the capacitors.

TABLE 6 R_(up) and R_(down) Electrode Factors Sample ElectrodeResistance Exp. (Feed Rate, Grind DOE Thickness Resistance R_(down) No.psi, Feed psi) Points (mm) R_(up) (Ohms) (Ohms) 1 250/85/60 0/0/0 0.1491.73 1.16 2 250/85/70 0/0/1 0.133 1.67 1.04 3 250/110/60 0/1/0 0.1531.63 1.07 4 250/110/70 0/1/1 0.147 1.64 1.07 5 800/85/60 1/0/0 0.1481.68 1.11 6 800/85/70 1/0/1 0.135 1.60 1.03 7 800/110/60 1/1/0 0.1501.80 1.25 8 800/110/70 1/1/1 0.153 1.54 1.05

To help visualize the above data and identify the data trends, wepresent FIGS. 1 m and 1 n, which graphically illustrate the relativeimportance of the three factors on the resulting R_(down) and normalizedC_(up). Note that in FIG. 1 m the Feed Rate and the Grind Pressure linesare substantially coincident.

Once again, increasing the inject pressure benefits both electroderesistance R_(down) (lowering it), and the normalized capacitance C_(up)(increasing it). Moreover, the effect of the inject pressure is greaterthan the effects of the other two factors. In fact, the effect of theinject pressure on the normalized capacitance overwhelms the effects ofthe feed rate and the grind pressure factors, at least for the factorranges investigated.

Additional data has been obtained relating C_(up) and R_(down) tofurther increases in the inject pressure. Here, the feed rate and thegrind pressure were kept constant at 250 units and 110 psi,respectively, while the inject pressure during production was set to 70psi, 85 psi, and 100 psi. Bar graphs in FIG. 1 p illustrate these data.As can be seen from these graphs, the normalized capacitance C_(up) waslittle changed with increasing inject pressure beyond a certain point,while electrode resistance displayed a drop of several percentage pointswhen the inject pressure was increased from 85 psi to 100 psi. Theinventors herein believe that increasing the inject pressure beyond 100psi would further improve electrode performance, particularly bydecreasing internal electrode resistance.

Although dry blending 18 and dry fibrillization step 20 have beendiscussed herein as two separate steps that utilize multiple apparatus,it is envisioned that steps 18 and 20 could be conducted in one stepwherein one apparatus receives dry particles 12, 14, and/or 16 asseparate streams to mix the particles and thereafter fibrillize theparticles. Accordingly, it is understood that the embodiments hereinshould not be limited by steps 18 and 20, but by the claims that follow.Furthermore, the preceding paragraphs describe in considerable detailinventive methods for dry fibrillizing carbon and binder mixtures tofabricate dry films, however, neither the specific embodiments of theinvention as a whole, nor those of its individual features should limitthe general principles described herein, which should be limited only bythe claims that follow.

It is identified that, in order to form a self supporting dry film withadequate physical as well as electrical properties for use in acapacitor as described further herein, sufficiently high shear forcesare needed. In contrast to the additive-based prior art fibrillizationsteps, the present invention provides such shear forces without usingprocessing aides or additives. Furthermore, with the present inventionno additives are used before, during, or after application of the shearforces. Numerous benefits derive from non-use of prior art additivesincluding: reduction of process steps and processing apparatus, increasein throughput and performance, the elimination or substantial reductionof residue and impurities that can derive from the use of additives andadditive-based process steps, as well as other benefits that arediscussed or that can be understood by those skilled in the art from thedescription of the embodiments that follows.

Referring back to FIG. 1 a, the illustrated process also includes steps21 and 23, wherein dry conductive particles 21 and dry binder 23 areblended in a dry blend step 19. Step 19, as well as added step 26, alsodo not utilize additives before, during, or after the steps. In oneembodiment, dry conductive particles 21 comprise conductive carbonparticles. In one embodiment, dry conductive particles 21 compriseconductive graphite particles. In one embodiment, it is envisioned thatconductive particles may comprise a metal powder of the like. In oneembodiment, dry binder 23 comprises a dry thermoplastic material. In oneembodiment, the dry binder comprises non-fibrillizable fluoropolymer. Inone embodiment, dry binder 23 comprises polyethylene particles. In oneembodiment, dry binder 23 comprises polypropylene or polypropylene oxideparticles. In one embodiment, the thermoplastic material is selectedfrom polyolefin classes of thermoplastic known to those skilled in theart. Other thermoplastics of interest and envisioned for potential useinclude homo and copolymers, olefinic oxides, rubbers, butadienerubbers, nitrile rubbers, polyisobutylene, poly(vinylesters),poly(vinylacetates), polyacrylate, fluorocarbon polymers, with a choiceof thermoplastic dictated by its melting point, metal adhesion, andelectrochemical and solvent stability in the presence of a subsequentlyused electrolyte. In other embodiments, thermoset and/or radiation settype binders are envisioned as being useful. The present invention,therefore, should not be limited by the disclosed and suggested binders,but only by the claims that follow.

As has been stated, a deficiency in the additive-based prior art is thatresidues of additive, impurities, and the like remain, even after one ormore long drying step(s). The existence of such residues is undesirablefor long-term reliability when a subsequent electrolyte impregnationstep is performed to activate an energy storage device electrode. Forexample, when an acetonitrile-based electrolyte is used, chemical and/orelectrochemical interactions between the acetonitrile and residues andimpurities can cause undesired destructive chemical processes in, and/ora swelling of, an energy storage device electrode. Other electrolytes ofinterest include carbonate-based electrolytes (ethylene carbonate,propylene carbonate, dimethylcarbonate), alkaline (KOH, NaOH), or acidic(H2SO4) water solutions. It is identified when processing additives aresubstantially reduced or eliminated from the manufacture of energystorage device structures, as with one or more of the embodimentsdisclosed herein, the prior art undesired destructive chemical and/orelectrochemical processes and swelling caused by the interactions ofresidues and impurities with electrolyte are substantially reduced oreliminated.

In one embodiment, dry carbon particles 21 and dry binder particles 23are used in a ratio of about 40%-60% binder to about 40%-60% conductivecarbon by weight. In step 19, dry carbon particles 21 and dry bindermaterial 23 are dry blended in a V-blender for about 5 minutes. In oneembodiment, the conductive carbon particles 21 comprise a mean diameterof about 10 microns. In one embodiment, the binder particles 23 comprisea mean diameter of about 10 microns or less. Other particle sizes arealso within the scope of the invention, and should be limited only bythe scope of the claims. In one embodiment, (further disclosed by FIG. 2a), the blend of dry particles provided in step 19 is used in a dry feedstep 22. In one embodiment (further disclosed by FIG. 2 g), the blend ofdry particles in step 19 may be used in a dry feed step 29, instead ofdry feed step 22. In order to improve suspension and characteristics ofparticles provided by container 19, a small amount of fibrillizablebinder (for example binder 16) may be introduced into the mix of the drycarbon particles 21 and dry binder particles 23, and dry fibrillized inan added dry fibrillization step 26 prior to a respective dry feed step22 or 29.

Referring now to FIG. 2 a, and preceding Figures as needed, there isseen one or more apparatus used for forming one or more energy devicestructure. In one embodiment, in step 22, the respective separatemixtures of dry particles formed in steps 19 and 20 are provided torespective containers 19 and 20. In one embodiment, dry particles fromcontainer 19 are provided in a ratio of about 1 gram to about 100 gramsfor every 1000 grams of dry particles provided by container 20. Thecontainers are positioned above a device 41 of a variety used by thoseskilled in the art to compact and/or calender materials into sheets. Thecompacting and/or calendering function provided by device 41 can beachieved by a roll-mill, calender, a belt press, a flat plate press, andthe like, as well as others known to those skilled in the art. Thus,although shown in a particular configuration, those skilled in the artwill understand that variations and other embodiments of device 41 couldbe provided to achieve one or more of the benefits and advantagesdescribed herein, which should be limited only by the claims thatfollow.

Referring now to FIG. 2 b, and preceding Figures as needed, there isseen an apparatus used for forming one or more electrode structure. Asshown in FIG. 2 b, the dry particles in containers 19 and 20 are fed asfree flowing dry particles to a high-pressure nip of a roll-mill 32. Asthey are fed towards the nip, the separate streams of dry particlesbecome intermixed and begin to loose their freedom of motion. It isidentified that use of relatively small particles in one or more of theembodiments disclosed herein enables that good particle mixing and highpacking densities can be achieved and that a concomitant lowerresistivity may be achieved as a result. The degree of intermixing canbe to an extent determined by process requirements and accordingly madeadjustments. For example, a separating blade 35 can be adjusted in botha vertical and/or a horizontal direction to change a degree of desiredintermixing between the streams of dry particles. The speed of rotationof each roll may be different or the same as determined by processrequirements. A resulting intermixed compacted dry film 34 exits fromthe roll-mill 32 and is self-supporting after only one compacting passthrough the roll-mill 32. The ability to provide a self supporting filmin one pass eliminates numerous folding steps and multiplecompacting/calendering steps that in prior art embodiments are used tostrengthen films to give them the tensile strength needed for subsequenthandling and processing. Because the intermixed dry film 34 can besufficiently self supporting after one pass through roll-mill 32, it caneasily and quickly be formed into one long integral continuous sheet,which can be rolled for subsequent use in a commercial scale manufactureprocess. The dry film 34 can be formed as a self-supporting sheet thatis limited in length only by the capacity of the rewinding equipment. Inone embodiment, the dry film is between 0.1 and 5000 meters long.Compared to some prior art additive based films which are described asnon-self supporting and/or small finite area films, the dryself-supporting films described herein are more economically suited forlarge scale commercial manufacture.

Referring now to FIG. 2 c, and preceding Figures as needed, there isseen a diagram representing the degree of intermixing that occursbetween particles from containers 19 and 20. In FIG. 2 c, a crosssection of intermixed dry particles at the point of application to thehigh-pressure nip of roll-mill 32 is represented, with “T” being anoverall thickness of the intermixed dry film 34 at a point of exit fromthe high-pressure nip. The curve in FIG. 2 c represents the relativeconcentration/amount of a particular dry particle at a given thicknessof the dry film 34, as measured from a right side of the dry film 34 inFIG. 2 b (y-axis thickness is thickness of film, and x-axis is relativeconcentration/amount of a particular dry particle). For example, at agiven thickness measured from the right side of the dry film 34, theamount of a type of dry particle from container 19 (as a percentage ofthe total intermixed dry particles that generally exists at a particularthickness) can be represented by an X-axis value “I”. As illustrated, ata zero thickness of the dry film 34 (represented at zero height alongthe Y-axis), the percentage of dry binder particles “I” from container19 will be at a maximum, and at a thickness approaching “T”, thepercentage of dry particles from container 19 will approach zero.

Referring now to FIG. 2 d, and preceding Figures as needed, there isseen a diagram illustrating a distribution of the sizes of dry binderand carbon particles. In one embodiment, the size distribution of drybinder and carbon particles provided by container 19 may be representedby a curve with a centralized peak, with the peak of the curverepresenting a peak quantity of dry particles with a particular particlesize, and the sides of the peak representing lesser amounts of dryparticles with lesser and greater particle sizes. In drycompacting/calendering step 24, the intermixed dry particles provided bystep 22 are compacted by the roll-mill 32 to form the dry film 34 intoan intermixed dry film. In one embodiment, the dry particles fromcontainer 19 are intermixed within a particular thickness of theresulting dry film 34 such that at any given distance within thethickness, the size distribution of the dry particles 19 is the same orsimilar to that existing prior to application of the dry particles tothe roll-mill 32 (i.e. as illustrated by FIG. 2 d). A similar type ofintermixing of the dry particles from container 20 also occurs withinthe dry film 34 (not shown).

In one embodiment, the process described by FIGS. 2 a-d is performed atan operating temperature, wherein the temperature can vary according tothe type of dry binder selected for use in steps 16 and 23, but suchthat the temperature is less than the melting point of the dry binder 23and/or is sufficient to soften the dry binder 16. In one embodiment, itis identified that when dry binder particles 23 with a melting point of150 degrees are used in step 23, the operating temperature at theroll-mill 32 is about 100 degrees centigrade. In other embodiments, thedry binder in step 23 may be selected to comprise a melting point thatvaries within a range of about 50 degrees centigrade and about 350degrees centigrade, with appropriate changes made to the operatingtemperature at the nip.

The resulting dry film 34 can be separated from the roll-mill 32 using adoctor blade, or the edge of a thin strip of plastic or other separationmaterial, including metal or paper. Once the leading edge of the dryfilm 34 is removed from the nip, the weight of the self-supporting dryfilm and film tension can act to separate the remaining exiting dry film34 from the roll-mill 32. The self-supporting dry film 34 can be fedthrough a tension control system 36 into a calender 38. The calender 38may further compact and densify the dry film 34. Additional calenderingsteps can be used to further reduce the dry film's thickness and toincrease tensile strength. In one embodiment, dry film 34 comprises acalendered density of about 0.50 to 0.70 gm/cm².

Referring now to FIGS. 2 e-f, there are seen carbon particlesencapsulated by dissolved binder of the prior art, and dry carbonparticles attached to dry binder of the present invention, respectively.In the prior art, capillary type forces caused by the presence ofsolvents diffuse dissolved binder particles in a wet slurry basedadhesive/binder layer into an attached additive-based electrode filmlayer. In the prior art, carbon particles within the electrode layerbecome completely encapsulated by the diffused dissolved binder, whichwhen dried couples the adhesive/binder and electrode film layerstogether. Subsequent drying of the solvent results in an interfacebetween the two layers whereat carbon particles within the electrodelayer are prevented by the encapsulating binder from conducting, therebyundesirably causing an increased interfacial resistance. In the priorart, the extent to which binder particles from the adhesive/binder layerare present within the electrode film layer becomes limited by the sizeof the particles comprising each layer, for example, as when relativelylarge particles comprising the wet adhesive/binder layer are blockedfrom diffusing into tightly compacted particles of the attachedadditive-based electrode film layer.

In contrast to the prior art, particles from containers 19 and 20 arebecome intermixed within dry film 34 such that each can be identified toexist within a thickness “T” of the dry film with a particularconcentration gradient. One concentration gradient associated withparticles from container 19 is at a maximum at the right side of theintermixed dry film 34 and decreases when measured towards the left sideof the intermixed dry film 34, and a second concentration gradientassociated with particles from container 20 is at a maximum at the leftside of the intermixed dry film 34 and decreases when measured towardsthe right side of the intermixed dry film 34. The opposing gradients ofparticles provided by container 19 and 20 overlap such thatfunctionality provided by separate layers of the prior art may beprovided by one dry film 34 of the present invention. In one embodiment,a gradient associated with particles from container 20 providesfunctionality similar to that of a separate prior art additive basedelectrode film layer, and the gradient associated with particles fromcontainer 19 provides functionality similar to that of a separate priorart additive based adhesive/binder layer. The present invention enablesthat equal distributions of all particle sizes can be smoothlyintermixed (i.e. form a smooth gradient) within the intermixed dry film34. It is understood that with appropriate adjustments to blade 35, thegradient of dry particles 19 within the dry film 34 can be made topenetrate across the entire thickness of the dry film, or to penetrateto only within a certain thickness of the dry film. In one embodiment,the penetration of the gradient of dry particles 19 is about 5 to 15microns. In part, due to the gradient of dry particles 19 that can becreated within dry film 34 by the aforementioned intermixing, it isidentified that a lesser amount of dry particles need be utilized toprovide a surface of the dry film with a particular adhesive property,than if dry particles 19 and dry particles 20 were pre-mixed throughoutthe dry film.

In the prior art, subsequent application of electrolyte to an additivebased two-layer adhesive/binder and electrode film combination may causethe binder, additive residues, and impurities within the layers todissolve and, thus, the two-layers to eventually degrade and/ordelaminate. In contrast, because the binder particles of the presentinvention are distributed evenly within the dry film according to theirgradient, and/or because no additives are used, and/or because thebinder particles may be selected to be substantially impervious,insoluble, and/or inert to a wide class of additives and/or electrolyte,such destructive delamination and degradation can be substantiallyreduced or eliminated.

The present invention provides one intermixed dry film 34 such that thesmooth transitions of the overlapping gradients of intermixed particlesprovided by containers 19 and 20 allow that minimized interfacialresistance is created. Because the dry binder particles 23 are notsubject to and/or do not dissolve during intermixing, they do notcompletely encapsulate particles 12, 14, and 21. Rather, as shown inFIG. 2 f, after compacting, and/or calendaring, and/or heating steps,dry binder particles 23 become softened sufficiently such that theyattach themselves to particles 12, 14, and 21. Because the dry binderparticles 23 are not completely dissolved as occurs in the prior art,the particles 23 become attached in a manner that leaves a certainamount of surface area of the particles 12, 14, and 21 exposed; anexposed surface area of a dry conductive particle can therefore makedirect contact with surface areas of other conductive particles. Becausedirect conductive particle-to-particle contact is not substantiallyimpeded by use of dry binder particles 23, an improved interfacialresistance over that of the prior art binder encapsulated conductiveparticles can be achieved.

The intermixed dry film 34 also exhibits dissimilar and asymmetricsurface properties at opposing surfaces, which contrasts to the priorart, wherein similar surface properties exist at opposing sides of eachof the separate adhesive/binder and electrode layers. The asymmetricsurface properties of dry film 34 may be used to facilitate improvedbonding and electrical contact to a subsequently used current collector(FIG. 3 below). For example, when bonded to a current collector, the onedry film 34 of the present invention introduces only one distinctinterface between the current collector and the dry film 34, whichcontrasts to the prior art, wherein a distinct first interfacialresistance boundary exists between a collector and additive basedadhesive/binder layer interface, and wherein a second distinctinterfacial resistance boundary exists between an additive-basedadhesive/binder layer and additive-based electrode layer interface.

Referring now to FIG. 2 g, and preceding Figures as needed, there isseen one or more apparatus used for the manufacture of one or morestructure described herein. FIG. 2 g illustrates apparatus similar tothat of FIG. 2 a, except that container 19 is positioned downstream fromcontainer 20. In one embodiment, in a step 29, the dry particlesprovided by container 19 are fed towards a high-pressure nip 38. Byproviding dry particles from steps 19 and 20 at two different points ina calender apparatus, it is identified that the temperature at each stepof the process may be controlled to take into account differentsoftening/melting points of dry particles that may be provided by steps19 and 20.

In FIG. 2 g, container 19 is disposed to provide dry particles 19 onto adry film 33. In FIG. 2 g, container 20 comprises dry particles 12, 14,and 16, which are dry fibrillized and provided in accordance withprinciples described above. A dry free flowing mixture from container 20may be compacted to provide the dry film 33 to be self-supporting afterone pass through a compacting apparatus, for example roll-mill 32. Theself-supporting continuous dry film 33 can be stored and rolled forlater use as an energy device electrode film, or may be used incombination with dry particles provided by container 19. For example, asin FIG. 2 g, dry adhesive/binder particles comprising a free flowingmixture of dry conductive carbon 21 and dry binder 23 from container 19may be fed towards dry film 33. In one embodiment, scatter coatingequipment similar to that used in textile and non-woven fabricindustries is contemplated for dispersion of the dry particles onto dryfilm 33. In one embodiment, the dry film 33 is formed from dry particles12, 14, and 16 as provided by container 20. The dry particles fromcontainer 19 may be compacted and/or calendared against and within thedry film 33 to form a subsequent dry film 34, wherein the dry particlesare embedded and intermixed within the dry film 34. Through choice oflocation of containers 19 and 20, separating blade 35, powder feed-rate,roll speed ratios, and/or surface of rolls, it is identified that theinterface between dry particles provided to form a dry particle basedelectrode film may be appropriately varied. An embedded/intermixed dryfilm 34 may be subsequently attached to a collector or wound onto astorage roll 48 for subsequent use.

Alternative means, methods, steps, and setups to those disclosed hereinare also within the scope of the present invention and should be limitedonly by the appended claims and their equivalents. For example, in oneembodiment, instead of the self supporting continuous dry film 33described herein, a commercially available prior art additive-basedelectrode film could be provided for subsequent calendering togetherwith dry particles provided by the container 19 of FIG. 2 g. Although aresulting two-layer film made in this manner would be at least in partadditive based, and could undesirably interact with subsequently usedelectrolyte, such a two-layer film would nevertheless not need toutilize, or be subject to the limitations associated with, a prior artslurry based adhesive/binder layer. In one embodiment, instead of thecontinuous dry film 33 of FIG. 2 g, a heated collector (not shown) couldbe provided, against which dry particles from container 19 couldcalendered. Such a combination of collector and adhered dry particlesfrom container 19 could be stored and provided for later attachment to aseparately provided electrode layer, which with appropriate apparatuscould be heat calendered to attach the dry binder 23 in dry particlesprovided by container 19 to the collector.

Referring to FIG. 3, and preceding Figures as needed, there is seen anapparatus used to bond a dry film to a current collector. In step 28, adry film 34 is bonded to a current collector 50. In one embodiment, thecurrent collector comprises an etched or roughened aluminum sheet, foil,mesh, screen, porous substrate, or the like. In one embodiment, thecurrent collector comprises a metal, for example, copper, aluminum,silver, gold, and the like. In one embodiment, current collectorcomprises a thickness of about 30 microns. Those skilled in the art willrecognize that if the electrochemical potential allows, other metalscould also be used as a collector 50.

In one embodiment, a current collector 50 and two dry film(s) 34 are fedfrom storage rolls 48 into a heated roll-mill 52 such that the currentcollector 50 is positioned between two self-supporting dry films 34. Inone embodiment, the current collector 50 may be pre-heated by a heater79. The temperature of the heated roll-mill 52 may be used to heat andsoften the dry binder 23 within the two intermixed dry films 34 suchthat good adhesion of the dry films to the collector 50 is effectuated.In one embodiment, a roll-mill 52 temperature of at the nip of the rollis between 100° C. and 300° C. In one embodiment, the nip pressure isselected between 50 pounds per linear inch (PLI) and 1000 PLI. Eachintermixed dry film 34 becomes calendared and bonded to a side of thecurrent collector 50. The two dry intermixed films 34 are fed into thehot roll nip 52 from storage roll(s) 48 in a manner that positions thepeak of the gradients formed by the dry particles from container 19directly against the current collector 50 (i.e. right side of a dry film34 illustrated in FIG. 2 b). After exiting the hot roll nip 52, it isidentified that the resulting calendared dry film and collector productcan be provided as a dry electrode 54 for use in an energy storagedevice, for example, as a double-layer capacitor electrode. In oneembodiment, the dry electrode 54 can be S-wrapped over chill rolls 56 toset the dry film 34 onto the collector 50. The resulting dry electrode54 can then be collected onto another storage roll 58. Tension controlsystems 51 can also be employed by the system shown in FIG. 3.

Other means, methods, and setups for bonding of films to a currentcollector 50 can be used to form energy storage device electrodes, whichshould be limited only by the claims. For example, in one embodiment(not shown), a film comprised of a combination of a prior artadditive-based electrode layer and embedded dry particles from acontainer 19 could be bonded to a current collector 50.

Referring to FIG. 4, and preceding Figures as needed, there is seen ablock diagram illustrating a method for reusing/recycling dry particlesand structures made therefrom. It has been identified that problems mayarise during one or more of the process steps described herein, forexample, if various process parameters vary outside a desiredspecification during a process step. It is identified, according toembodiments described further herein, that dry particles 12, 14, 16, 21,23, dry films 33 and 34, and one or more structures formed therefrom maybe reused/recycled despite such problems arise, if so desired or needed.Because of use of additives, prior art process are unable provide suchreuse/recycle process steps. In general, because one or more of theembodiments described herein do not utilize processing additives, theproperties of the dry particles 12, 14, 16, 21, and/or 23 are notadversely altered ensuing process steps. Because solvent, lubricants, orother liquids are not used, impurities and residues associated therewithdo not degrade the quality of the dry particles 12, 14, 16, 21, and/or23, allowing the particles to be reused one or more times. Becauseminimal or nor drying times are needed, dry particles 12, 14, 16, 21,and/or 23 may be reused quickly without adversely affecting throughputof the dry process. Compared against the prior art, it has beenidentified that the dry particles and/or dry structures formed therefrommay be reused/recycled such that overall process yield and cost can bereduced without affecting overall quality.

It is identified that dry particles 12, 14, 16, 21, and/or 23 may bereused/recycled after being processed by a particular dry process step19, 20, 22, 24, 26, 28, and/or 29. For example, in one embodiment, afterdry process step 18 or 20, if it is determined that a defect in dryparticles 12, 14, 16, and/or a structure formed thereform is present,the resulting material may be collected in a dry process step 25 forreuse or recycling. In one embodiment, dry particles 12, 14, and 16 maybe returned and reprocessed without addition of any other dry particles,or may be returned and added to fresh new additional particles 12, 14,and/or 16. Dry particles provided for recycling by step 25 may bereblended by dry blend step 18, and further processed according to oneor more embodiments described herein. In one embodiment, a dry film 33comprised of dry particles 12, 14, and 16 as described above in FIG. 2g, and provided as a self-supporting film 33 by step 24, may be recycledin step 25. In one embodiment, after dry process step 19, 26, or 29, ifit is determined that a defect in dry particles 21, 23, or a structureformed therefrom is present, the resulting material may be collected ina dry process step 25 and returned for recycling. In one embodiment, dryparticles 21 and 23 may be returned and reprocessed without addition ofany other dry particles, or may be returned and added to freshadditional particles 21 or 23. Dry particles provided for recycling bystep 25 may be reblended by dry blend step 19, and further processedaccording to one or more embodiments described herein. In oneembodiment, dry particles 12, 14, 16, 21, and 23 as provided as aself-supporting film 34 by step 24 may be recycled in step 25. Prior toreuse, the dry film 33 or 34 can be sliced, chopped, or other wise bereduced in size so as to be more easily blended, by itself, or incombination with additional new dry particles 12, 14, 16, 21, and/or 23.

If after bonding dry film 34 to a collector, a defect in the resultingelectrode is found, it is envisioned that the combination of dry filmand bonded collector could also be sliced chopped, or otherwise reducedin size so as to be easily blended. Because the collector may comprise aconductor, it is envisioned that the collector portion of the recycledelectrode could provide similar functionality to that provided by thedry conductive particles. It is envisioned that the recycled/reused dryfilm 34 and collector mixture could be used in combination withadditional new dry particles 12, 14, 16, 21, and/or 23.

In one embodiment, it is envisioned that a certain percentage of dryreused/recycled dry material provided by step 25 could be mixed with acertain percentage of fresh dry particles 12, 14, 16, 21, and/or 23. Inone embodiment a mix of fresh particles 12, 14, 16, 21, and/or 23; anddry reused/recycled material resulting from step 25 comprises a 50/50mix. Other mixtures of new and old dry structures are also within thescope of the invention. In one embodiment, over all particle percentagesby weight, after recycle/reuse steps described herein, may comprisepercentages previously described herein, or other percentages as needed.In contrast to embodiments of intermixed film 34 discussed above, thoseskilled in the art will identify that a dry film 34 comprising one ormore recycled structures may, (depending on what particular point arecycle/use step was performed), comprise a dry film with less, or evenno, particle distribution gradients (i.e. an evenly intermixed dryfilm).

Referring now to FIGS. 5 a and 5 b, and preceding Figures as needed,there are seen structures of an energy storage device. In FIG. 5 a,there are shown cross-sections of four intermixed dry films 34, whichare bonded to a respective current collector 50 according to one or moreembodiments described previously herein. First surfaces of each of thedry films 34 are coupled to a respective current collector 50 in aconfiguration that is shown as a top dry electrode 54 and a bottom dryelectrode 54. According to one or more of the embodiments discussedpreviously herein, the top and bottom dry electrodes 54 are formed froma blend of dry particles without use of any additives. In oneembodiment, the top and bottom dry electrodes 54 are separated by aseparator 70. In one embodiment, separator 70 comprises a porous papersheet of about 30 microns in thickness. Extending ends of respectivecurrent collectors 50 are used to provide a point at which electricalcontact can be effectuated. In one embodiment, the two dry electrodes 54and separators 70 are subsequently rolled together in an offset mannerthat allows an exposed end of a respective collector 50 of the topelectrode 54 to extend in one direction and an exposed end of acollector 50 of the bottom electrode 54 to extend in a second direction.The resulting geometry is known to those skilled in the art as ajellyroll and is illustrated in a top view by FIG. 5 b.

Referring now to FIG. 5 b, and preceding Figures as needed, first andsecond electrodes 54, and two separators 70 are rolled about a centralaxis to form a rolled energy storage device electrode 200. In oneembodiment, the electrode 200 comprises two dry films 34, each dry filmcomprising a width and a length. In one embodiment, one square meter ofa 150 micron thick dry film 34 weighs about 0.1 kilogram. In oneembodiment, the dry films 34 comprise a thickness of about 80 to 260microns. In one embodiment, a width of the dry films comprises betweenabout 10 to 300 mm. In one embodiment, a length is about 0.1 to 5000meters and the width is between 30 and 150 mm. Other particulardimensions may be may be determined by a required final energy storagedevice storage parameter. In one embodiment, the storage parameterincludes values between 1 and 5000 Farads. With appropriate changes andadjustments, other dry film 34 dimensions and other capacitance arewithin the scope of the invention. Those skilled in the art willunderstand that offset exposed current collectors 50 (shown in FIG. 5 a)extend from the roll, such that one collector extends from one end ofthe roll in one direction and another collector extends from an end ofthe roll in another direction. In one embodiment, the collectors 50 maybe used to make electric contact with internal opposing ends of a sealedhousing, which can include corresponding external terminals at eachopposing end for completing an electrical contact.

Referring now to FIG. 6, and preceding Figures as needed, duringmanufacture, a rolled electrode 1200 made according to one or more ofthe embodiments disclosed herein is inserted into an open end of ahousing 2000. An insulator (not shown) is placed along a top peripheryof the housing 2000 at the open end, and a cover 2002 is placed on theinsulator. During manufacture, the housing 2000, insulator, and cover2002 may be mechanically curled together to form a tight fit around theperiphery of the now sealed end of the housing, which after the curlingprocess is electrically insulated from the cover by the insulator. Whendisposed in the housing 2000, respective exposed collector extensions1202 of electrode 1200 make internal contact with the bottom end of thehousing 2000 and the cover 2002. In one embodiment, external surfaces ofthe housing 2000 or cover 2002 may include or be coupled to standardizedconnections/connectors/terminals to facilitate electrical connection tothe rolled electrode 1200 within the housing 2000. Contact betweenrespective collector extensions 1202 and the internal surfaces of thehousing 2000 and the cover 2002 may be enhanced by welding, soldering,brazing, conductive adhesive, or the like. In one embodiment, a weldingprocess may be applied to the housing and cover by an externally appliedlaser welding process. In one embodiment, the housing 2000, cover 2002,and collector extensions 1202 comprise substantially the same metal, forexample, aluminum. An electrolyte can be added through a filling/sealingport (not shown) to the sealed housing 1200. In one embodiment, theelectrolyte is 1.5 M tetramethylammonium or tetrafluoroborate inacetonitrile solvent. After impregnation and sealing, a finished productis thus made ready for commercial sale and subsequent use.

Although the particular systems and methods herein shown and describedin detail are capable of attaining the above described objects of theinvention, it is understood that the description and drawings presentedherein represent some, but not all, embodiments that are broadlycontemplated. Structures and methods that are disclosed may thuscomprise configurations, variations, and dimensions other than thosedisclosed. For example, other classes of energy storage devices thatutilize electrodes and adhesives as described herein are within thescope of the present invention, including batteries and fuel cells.Also, different housings may comprise coin-cell type, clamshell type,prismatic, cylindrical type geometries, as well as others as are knownto those skilled in the art. For a particular type of housing, it isunderstood that appropriate changes to electrode geometry may berequired, but that such changes would be within the scope of thoseskilled in the art. It is also contemplated that an energy storagedevice made according to dry principles described herein may comprisetwo different electrode films that differ in compositions and/ordimensions (i.e. asymmetric electrodes). Additionally, it iscontemplated that principles disclosed herein could be utilized incombination with a carbon cloth type electrode. Thus, the scope of thepresent invention fully encompasses other embodiments that may becomeobvious to those skilled in the art and that the scope of the presentinvention is accordingly limited by nothing other than the appendedclaims and their equivalents.

1. A method of making an energy storage device electrode, the methodcomprising: forming a first electrode film from a plurality ofparticles; and reusing one or more of the plurality of particles to forma second film.
 2. The method of claim 1, wherein the plurality ofparticles are dry fibrillized.
 3. The method of claim 2, wherein theoperation of reusing comprises dry fibrillizing the particles after theparticles are used to make the first electrode film.
 4. The method ofclaim 1, further comprising coupling a first side of the second film toa collector.
 5. The method of claim 1, wherein the one or more of theplurality of particles reused to form the second film comprisefibrillizable fluoropolymer particles, activated carbon particles, andconductive particles.
 6. The method of claim 5, wherein the bindercomprises a fluoropolymer.
 7. The method of claim 5, wherein theconductive particles comprise conductive carbon particles.
 8. The methodof claim 1, wherein the first film is self-supporting.
 9. The method ofclaim 1, wherein the second film is self-supporting.
 10. The method ofclaim 1, wherein the plurality of particles comprise conductive carbonparticles and activated carbon particles.
 11. The method of claim 1,wherein the first and second films are heated dry films.
 12. The methodof claim 1, wherein the second film comprises a density of about 0.50 to0.70 gm/cm².
 13. The method of claim 1, wherein the first film comprisesbetween about 80% to 95% activated carbon, between about 0% to 15%conductive carbon, and between about 3% to 15% fibrillizablefluoropolymer.
 14. The method of claim 13, wherein the first filmfurther comprises a thermoplastic.
 15. The method of claim 1, whereinthe second film comprises a length of at least one meter.
 16. The methodof claim 1, wherein the first film comprises substantially no processingadditive.
 17. The method of claim 1, wherein reusing operation comprisesforming the second film using substantially no processing additive. 18.The method of claim 17, wherein the processing additives includehydrocarbons, high boiling point solvents, antifoaming agents,surfactants, dispersion aids, water, pyrrolidone, mineral spirits,ketones, naphtha, acetates, alcohols, glycols, toluene, xylene, and/orisoparaffinic fluids.
 19. The method of claim 1, wherein the one or moreof the plurality of particles reused to form the second film comprisedry processed recycled binder particles and conductive particles. 20.The method of claim 1, wherein the second film comprises aself-supporting dry intermixed film structure comprised of reused carbonand binder particles.
 21. The method of claim 20, wherein the reusingoperation comprises forming the second film comprises with substantiallyno processing additive.
 22. The method of claim 1, wherein the one ormore of the plurality of particles reused to form the second filmcomprise dry processed recycled binder particles and activated carbonparticles.
 23. The method of claim 22, wherein the second film is bothconductive and adhesive.
 24. The method of claim 23, wherein the secondfilm is coupled directly to a current collector.
 25. A method of makingan energy storage device electrode, the method comprising: dryprocessing a dry mixture of binder particles, activated carbon particlesand recycled conductive particles to form an electrode film.
 26. Themethod of claim 25, wherein the binder particles comprise athermoplastic.
 27. The method of claim 25, wherein electrode film iscoupled to a collector.
 28. The method of claim 25, wherein the recycledconductive particles comprise recycled conductive carbon particles. 29.The method of claim 25, wherein the dry processing operation comprisesfibrillizing the binder particles.
 30. The method of claim 25, whereinthe binder particles comprise fibrillizable fluoropolymer particles. 31.The method of claim 25, wherein the electrode film comprises aself-supporting film.
 32. The method of claim 25, wherein the binderparticles are recycled.
 33. The method of claim 25, wherein theactivated carbon particles are recycled.
 34. The method of claim 25,wherein the dry processing operation comprises substantially noprocessing additive.
 35. A method of making an energy storage deviceelectrode, the method comprising: dry processing a dry mixture ofactivated carbon particles and recyclable binder particles to form aself-supporting electrode film.
 36. The method of claim 35, furthercomprising coupling the self-supporting electrode film to a collector.37. The method of claim 35, wherein the electrode film comprises acapacitor electrode film.
 38. The method of claim 35, wherein the dryprocessing operation comprises fibrillizing the recyclable binderparticles.
 39. The method of claim 35, wherein the recyclable binderparticles comprise recyclable fibrillizable fluoropolymer particles. 40.The method of claim 35, wherein the recyclable binder particles arerecycled.
 41. The method of claim 35, wherein the activated carbonparticles are recyclable.
 42. The method of claim 41, wherein therecyclable activated carbon particles are recycled.
 43. The method ofclaim 35, wherein the dry processing operation comprises substantiallyno processing additive.